1. Field of the Invention
The invention relates to a method for operating a motor vehicle having at least one drive unit in the form of an internal combustion engine. The invention also relates to a corresponding apparatus.
2. Description of the Related Art
A drive of a motor vehicle is generally actuated by an accelerator pedal with which an engine power is controlled. In modern vehicles, it has become customary to design the accelerator pedal as an electronic accelerator pedal or E-gas for short. Thus, the accelerator pedal no longer acts on the drive unit mechanically directly by means of a linkage or cable, but rather by means of an engine control means. In this case, a sensor is provided and informs a corresponding control unit of the engine control means of an acceleration or driver command made by the driver. This sensor also is called a pedal value transmitter. The sensor transmits an accelerator pedal position, an accelerator pedal angle or an accelerator pedal travel to the control unit generally analogously in the form of voltage values.
The accelerator pedal sensor generally is equipped with two resistors or potentiometers with different operating ranges and separate lines.
Accelerator pedals have a defined pedal force/pedal travel characteristic curve. In the case of a hybrid vehicle, a changeover is made from an electric driving mode to driving using an internal combustion engine without the driver being able to identify this changeover when pressing the accelerator pedal. Therefore, in the case of a hybrid vehicle, purely electric driving is virtually impossible to achieve by deliberate operation of the accelerator pedal.
U.S. Pat. No. 7,699,129 B2 discloses an accelerator pedal that provides a driver with feedback when a motor is being started. This feedback in the form of a sudden increase in return force is coupled with a threshold position of the accelerator pedal.
U.S. Pat. No. 7,971,506 B2 discloses an adaptable position-kickdown locking mechanism to provide a driver of a motor vehicle with force feedback by virtue of an accelerator pedal of an E-gas system before a transition is made to kickdown.
DE 10 2010 039 377 A1 discloses a method for operating a drive train of a motor vehicle. The drive train comprises a drive assembly in the form of a hybrid drive with an internal combustion engine and an electrical machine. A transmission is connected between the drive assembly and a drive. Furthermore, the internal combustion engine can be decoupled from the drive and stopped in the event of purely electric driving by the electrical machine. A time for starting the internal combustion engine with the aid of the electrical machine is determined as a function of operating parameters of the drive train. The imminent starting of the internal combustion engine with the aid of the electrical machine is announced haptically to a driver by the buildup of a counterpressure on an accelerator pedal.
DE 10 2007 011 739 A1 discloses a hybrid motor vehicle with a drive unit that can be operated both jointly and individually to generate drive torque. A device also is provided for prespecifying a driver command. The device is formed so that a force stage with an increased return force is present within the adjustment range of the device.
DE 10 2008 000 577 A1 discloses a method for operating a vehicle having a hybrid drive so that the driver is informed about various drive units being connected by virtue of a return force of the accelerator pedal that is increased at a corresponding point.
WO 2010/052236 A1 discloses an accelerator pedal with a zero return force at a specific speed.
The object of the invention is to indicate an action, for example a changeover from an electric driving mode to a driving mode using the internal combustion engine or deactivation of cylinder switch-off, to a driver in good time. More particularly, a motor vehicle driver should be informed at an early stage when a specific action is initiated in the drive train, for example deactivation of cylinder switch-off or a changeover from an electric driving mode to a driving mode using an internal combustion engine.